Color classification shown in the listing refers to the wire diameter (specification). The copper wire is manufactured to national standard specifications. Gauge refers to the diameter of the bent copper wire, i.e. the inner diameter without the paint film. Specifications Product: enameled wire, also known as insulated copper wire Construction: inner layer of pure copper; surface insulating paint; polyester patent leather Packing: 1 piece x enameled wire (500 g / 17.6 oz) Voltage and temperature Voltage class: 3000V–5000V Temperature resistance: 130–180 degrees Celsius Key features Direct welding capability: can be directly welded without removing insulation frequency resistance: suitable for frequency applications Portable: easy to carry and handle What this delivers Reliable copper conductor with durable insulation for coil winding and electrical applications National standard copper wire alignment ensures compatibility with standard components and assemblies Solid mass per pack (500 g) provides ample length for multiple projects Practical use scenarios Winding coils for transformers and inductors in electronic projects and hobbyist builds Building small motors or actuators that require enamelcoated copper windings Prototyping, repairs, or retrofitting where directweld capability speeds assembly and testing Notes Gauge indicates the inner diameter of the bent copper conductor before the paint film is applied Color classification reflects the wire diameter/spec in the listing and does not change the national standard specification of the copper wire